// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
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//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
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package org.springframework.asm;

import java.util.Arrays;

/**
 * A constant whose value is computed at runtime, with a bootstrap method.
 *
 * @author Remi Forax
 */
public final class ConstantDynamic {

	/**
	 * The constant name (can be arbitrary).
	 */
	private final String name;

	/**
	 * The constant type (must be a field descriptor).
	 */
	private final String descriptor;

	/**
	 * The bootstrap method to use to compute the constant value at runtime.
	 */
	private final Handle bootstrapMethod;

	/**
	 * The arguments to pass to the bootstrap method, in order to compute the constant value at
	 * runtime.
	 */
	private final Object[] bootstrapMethodArguments;

	/**
	 * Constructs a new {@link ConstantDynamic}.
	 *
	 * @param name                     the constant name (can be arbitrary).
	 * @param descriptor               the constant type (must be a field descriptor).
	 * @param bootstrapMethod          the bootstrap method to use to compute the constant value at runtime.
	 * @param bootstrapMethodArguments the arguments to pass to the bootstrap method, in order to
	 *                                 compute the constant value at runtime.
	 */
	public ConstantDynamic(
			final String name,
			final String descriptor,
			final Handle bootstrapMethod,
			final Object... bootstrapMethodArguments) {
		this.name = name;
		this.descriptor = descriptor;
		this.bootstrapMethod = bootstrapMethod;
		this.bootstrapMethodArguments = bootstrapMethodArguments;
	}

	/**
	 * Returns the name of this constant.
	 *
	 * @return the name of this constant.
	 */
	public String getName() {
		return name;
	}

	/**
	 * Returns the type of this constant.
	 *
	 * @return the type of this constant, as a field descriptor.
	 */
	public String getDescriptor() {
		return descriptor;
	}

	/**
	 * Returns the bootstrap method used to compute the value of this constant.
	 *
	 * @return the bootstrap method used to compute the value of this constant.
	 */
	public Handle getBootstrapMethod() {
		return bootstrapMethod;
	}

	/**
	 * Returns the number of arguments passed to the bootstrap method, in order to compute the value
	 * of this constant.
	 *
	 * @return the number of arguments passed to the bootstrap method, in order to compute the value
	 * of this constant.
	 */
	public int getBootstrapMethodArgumentCount() {
		return bootstrapMethodArguments.length;
	}

	/**
	 * Returns an argument passed to the bootstrap method, in order to compute the value of this
	 * constant.
	 *
	 * @param index an argument index, between 0 and {@link #getBootstrapMethodArgumentCount()}
	 *              (exclusive).
	 * @return the argument passed to the bootstrap method, with the given index.
	 */
	public Object getBootstrapMethodArgument(final int index) {
		return bootstrapMethodArguments[index];
	}

	/**
	 * Returns the arguments to pass to the bootstrap method, in order to compute the value of this
	 * constant. WARNING: this array must not be modified, and must not be returned to the user.
	 *
	 * @return the arguments to pass to the bootstrap method, in order to compute the value of this
	 * constant.
	 */
	Object[] getBootstrapMethodArgumentsUnsafe() {
		return bootstrapMethodArguments;
	}

	/**
	 * Returns the size of this constant.
	 *
	 * @return the size of this constant, i.e., 2 for {@code long} and {@code double}, 1 otherwise.
	 */
	public int getSize() {
		char firstCharOfDescriptor = descriptor.charAt(0);
		return (firstCharOfDescriptor == 'J' || firstCharOfDescriptor == 'D') ? 2 : 1;
	}

	@Override
	public boolean equals(final Object object) {
		if (object == this) {
			return true;
		}
		if (!(object instanceof ConstantDynamic)) {
			return false;
		}
		ConstantDynamic constantDynamic = (ConstantDynamic) object;
		return name.equals(constantDynamic.name)
				&& descriptor.equals(constantDynamic.descriptor)
				&& bootstrapMethod.equals(constantDynamic.bootstrapMethod)
				&& Arrays.equals(bootstrapMethodArguments, constantDynamic.bootstrapMethodArguments);
	}

	@Override
	public int hashCode() {
		return name.hashCode()
				^ Integer.rotateLeft(descriptor.hashCode(), 8)
				^ Integer.rotateLeft(bootstrapMethod.hashCode(), 16)
				^ Integer.rotateLeft(Arrays.hashCode(bootstrapMethodArguments), 24);
	}

	@Override
	public String toString() {
		return name
				+ " : "
				+ descriptor
				+ ' '
				+ bootstrapMethod
				+ ' '
				+ Arrays.toString(bootstrapMethodArguments);
	}
}
